In the field of physical medicine and rehabilitation, doctors and physical therapists are often called upon to assess the functional capacity of a particular patient. This may arise in the context of testing a company's new employees to determine whether they are physically capable of performing the tasks involved in a given job, testing previously injured employees to determine whether they are capable of returning to work, or testing those injured in an accident to determine the scope of the injury, such as for an insurance settlement or a law suit. Therapists typically run a series of tests, which can include physical tests, visual observations and verbal questions, to assess the ability of a patient to lift and move objects and/or to tolerate various postures, positions or activities. For clarity's sake, the test giver will be referred to as the "therapist" throughout. It will be appreciated that the test giver could be a doctor, nurse, physical therapist, exercise physiologist or other such person.
While there is a great need for an accurate functional capacity assessment, there currently exists no system which can repeatedly and accurately test the weight that a person can safely lift. This problem is compounded by an uncertain degree of effort on the part of the patient. In certain circumstances, the patient may believe it is in his best interests to exert a less than maximal effort. Consequently, the patient may refuse to lift a weight above a certain weight, may lift a weight slowly, may complain of pain during certain weighted movements (while not, in fact, in pain), or may otherwise adjust his performance in an attempt to reflect an injury. While current testing methods can provide some useful information when administered by a skilled therapist, if the dishonest patient is relatively consistent, it can be difficult to ascertain when he is faking and when the patient is exerting a true effort when the therapist relies exclusively upon current testing methods.
Current assessment protocols generally require the patient to proceed through a series of movements. Some of these movements employ only the body weight of the patient, or can be performed using isokinetic or isometric machines. Alternatively, the movements can be weighted, providing additional resistance to the patient. The therapist observes the movements of the patient, both how the torso and limbs move, as well as any facial expressions or other outward signals the patient may give. Using this information, the therapist determines what he or she believes to be the patient's maximal effort, whether that patient is faking their effort, and whether that patient is capable of returning to work. In other tests, the patient himself states when he believes he has lifted a maximum weight or performed a task to his fullest capacity. Obviously, these tests are highly subjective, relying on the skill of the therapist as well as the current physical and emotional states of the therapist and the patient. There are a variety of testing techniques that employ the above methodology. None of these tests have been fully standardized so as to eliminate subjectivity and bias. Each therapist administers the tests differently, affecting the patients and their responses to the tests, adding additional uncertainty. Because the results of the tests contain a high level of uncertainty, they can only be of limited value.
U.S. Pat. No. 4,813,436 is directed to a motion analysis system employing various operating modes and including a video camera. Markers are secured to the various joints of the test subjects body. Pressure sensitive shoes or insoles are worn by the subject as he walks or runs on a treadmill. The subject is video taped using two distinct video cameras. The video signal is stored and then processed to provide digitized data concerning the movement of the markers. Meanwhile, the pressure sensitive insoles provide signals which indicate the pressure applied by the subjects foot while on the treadmill. The digitized information from the video cameras is used to display the gait, the angular position of the various joints of the patient and other information related to the walking characteristics of the subject.
U.S. Pat. No. 4,416,293 is directed to a method and apparatus for recording gait analysis in podiatric diagnosis and treatment. The subject is instructed to walk or run on a treadmill while being video taped. This video is displayed for review by the subject and the physical therapist.
U.S. Pat. No. 5,524,645 is directed to an objective measurement tool for evaluating medical therapy outcome in accordance with quantified physical therapy data. Once the physical parameters have been established, they are tracked during physical therapy. A measure of the patient's progress can, therefore, be calculated. This measure can be used to justify additional physical therapy or to indicate when further physical therapy would not be particularly effective.
None of these systems solve the problems addressed by the system and method of the current invention. Further, various prior art systems are large and expensive and therefore not well-suited to on site testing.